Propylene glycol toxicity in an adolescent secondary to chronic cornstarch ingestion.

Propylene glycol (PG) is a diol (a double alcohol) that is commonly used as a food additive to preserve shelf life and enhance flavors, texture, and appearance. Although PG makes up only a small percentage of cornstarch, ingestion of large doses can cause lactic acidosis leading to hyperosmolarity, high anion gap metabolic acidosis (HAGMA), and a sepsis-like syndrome. A 17-year-old female presented to our emergency department (ED) with chronic chest pain, dyspnea, nausea, and vomiting. Laboratory testing showed an elevated anion gap of 18 mEq/L with no osmolar gap. Toxicology screening was negative. Twelve hours after ED arrival, she admitted to consuming one box of cornstarch daily for the past 6 months. She was admitted to the intensive care unit (ICU) with multisystem organ failure due to propylene glycol toxicity. After empiric treatment with fomepizole and continuous renal replacement therapy, her clinical status gradually improved. This case highlights the importance of obtaining a thorough dietary history in patients with suspected toxicities, especially when laboratory values demonstrate an unexplained HAGMA and/or lactic acidosis. Prompt recognition and therapeutic intervention with fomepizole, a potent inhibitor of alcohol dehydrogenase, is essential in reducing life-threatening sequelae following toxic alcohol ingestions.

Treatment Guidelines for Hyponatremia: Stay the Course.

International guidelines designed to minimize the risk of complications that can occur when correcting severe hyponatremia have been widely accepted for a decade. On the basis of the results of a recent large retrospective study of patients hospitalized with hyponatremia, it has been suggested that hyponatremia guidelines have gone too far in limiting the rate of rise of the serum sodium concentration; the need for therapeutic caution and frequent monitoring of the serum sodium concentration has been questioned. These assertions are reminiscent of a controversy that began many years ago. After reviewing the history of that controversy, the evidence supporting the guidelines, and the validity of data challenging them, we conclude that current safeguards should not be abandoned. To do so would be akin to discarding your umbrella because you remained dry in a rainstorm. The authors of this review, who represent 20 medical centers in nine countries, have all contributed significantly to the literature on the subject. We urge clinicians to continue to treat severe hyponatremia cautiously and to wait for better evidence before adopting less stringent therapeutic limits.

Review of Clinical Disorders Causing Metabolic Acidosis.

The various mechanisms responsible for the development of metabolic acidosis are briefly reviewed, and the metabolic acidoses are categorized both by mechanism and by the presence or absence of an increased anion gap. When a diagnosis of metabolic acidosis is established, it becomes imperative to identify the primary causative etiology as quickly as possible. This is often readily apparent from the history and physical exam (ie, diabetic ketoacidosis when the glucose is very high in a patient with diabetes mellitus; lactic acidosis in a patient with sepsis and hypotension, etc.). However, when the etiology is not obvious, it is very helpful to determine if the metabolic acidosis is of the hyperchloremic or high-anion-gap type (or a combination of both). Once this categorization has been established, a stepwise consideration of each of the potential causative etiologies will usually direct the clinician to order the appropriate diagnostic studies.

Approach to Patients With High Anion Gap Metabolic Acidosis: Core Curriculum 2021.

The anion gap (AG) is a mathematical construct that compares the blood sodium concentration with the sum of the chloride and bicarbonate concentrations. It is a helpful calculation that divides the metabolic acidoses into 2 categories: high AG metabolic acidosis (HAGMA) and hyperchloremic metabolic acidosis-and thereby delimits the potential etiologies of the disorder. When the [AG] is compared with changes in the bicarbonate concentration, other occult acid-base disorders can be identified. Furthermore, finding that the AG is very small or negative can suggest several occult clinical disorders or raise the possibility of electrolyte measurement artifacts. In this installment of AJKD's Core Curriculum in Nephrology, we discuss cases that represent several very common and several rare causes of HAGMA. These case scenarios highlight how the AG can provide vital clues that direct the clinician toward the correct diagnosis. We also show how to calculate and, if necessary, correct the AG for hypoalbuminemia and severe hyperglycemia. Plasma osmolality and osmolal gap calculations are described and when used together with the AG guide appropriate clinical decision making.

Pseudohyperchloremia and Negative Anion Gap - Think Salicylate!

BACKGROUND: Pseudohyperchloremia results in a very low or negative anion gap. Historically, the most common cause of this artifact was bromide poisoning. Bromide salts have been removed from most medications and bromism has become very uncommon. More recently, the introduction of chloride ion selective sensing electrodes (Cl-ISE) has generated a new cause of pseudohyperchloremia-salicylate poisoning. We describe 5 such patients and quantitate the error generated by this measurement artifact. METHODS: The magnitude of artifactual hyperchloremia generated by high salicylate levels was quantified in 5 patients by measuring chloride concentration with several Cl-ISEs from different manufacturers and with Cl-ISEs of different "ages," and comparing these results to measurements with a chloridometer (coulometric titration), which is free of the salicylate artifact. RESULTS: Cl-ISEs from different manufacturers generated a wide range of artifactual chloride concentration elevation. Furthermore, the same Cl-ISE generated increasingly severe pseudohyperchloremia as it was repeatedly reused over time and "aged." CONCLUSIONS: Salicylate interferes with measurement of the blood chloride concentration when a Cl-ISE is used. The severity of this artifact is related to the salicylate level, the specific Cl-ISE, and the "age" of the electrode. Toxic blood salicylate levels can generate marked pseudohyperchloremia, and consequently, an artifactual very small or negative anion gap. The large anion gap metabolic acidosis typical of salicylate poisoning is masked by this artifact. Salicylate has become the most common cause of pseudohyperchloremia, and physicians should immediately consider salicylate poisoning whenever the combination of hyperchloremia and a very small or negative anion gap is reported by the laboratory.

Clinical Management of Hyperkalemia.

Hyperkalemia is an electrolyte abnormality with potentially life-threatening consequences. Despite various guidelines, no universally accepted consensus exists on best practices for hyperkalemia monitoring, with variations in precise potassium (K+) concentration thresholds or for the management of acute or chronic hyperkalemia. Based on the available evidence, this review identifies several critical issues and unmet needs with regard to the management of hyperkalemia. Real-world studies are needed for a better understanding of the prevalence of hyperkalemia outside the clinical trial setting. There is a need to improve effective management of hyperkalemia, including classification and K+ monitoring, when to reinitiate previously discontinued renin-angiotensin-aldosterone system inhibitor (RAASi) therapy, and when to use oral K+-binding agents. Monitoring serum K+ should be individualized; however, increased frequency of monitoring should be considered for patients with chronic kidney disease, diabetes, heart failure, or a history of hyperkalemia and for those receiving RAASi therapy. Recent clinical studies suggest that the newer K+ binders (patiromer sorbitex calcium and sodium zirconium cyclosilicate) may facilitate optimization of RAASi therapy. Enhancing the knowledge of primary care physicians and internists with respect to the safety profiles of these newer K+ binders may increase confidence in managing patients with hyperkalemia. Lastly, the availability of newer K+-binding agents requires further study to establish whether stringent dietary K+ restrictions are needed in patients receiving K+-binder therapy. Individualized monitoring of serum K+ among patients with an increased risk of hyperkalemia and the use of newer K+-binding agents may allow for optimization of RAASi therapy and more effective management of hyperkalemia.

Antecedent Administration of Angiotensin-Converting Enzyme Inhibitors or Angiotensin II Receptor Antagonists and Survival After Hospitalization for COVID-19 Syndrome.

Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) utilizes the angiotensin-converting enzyme-2 (ACE-2) receptor to enter human cells. Angiotensin-converting enzyme inhibitors (ACEI) and angiotensin II receptor antagonists (ARB) are associated with ACE-2 upregulation. We hypothesized that antecedent use of ACEI/ARB may be associated with mortality in coronavirus disease 2019 (COVID-19). Methods and Results We used the Coracle registry, which contains data of patients hospitalized with COVID-19 in 4 regions of Italy, and restricted analyses to those ≥50 years of age. The primary outcome was in-hospital mortality. Among these 781 patients, 133 (17.0%) used an ARB and 171 (21.9%) used an ACEI. While neither sex nor smoking status differed by user groups, patients on ACEI/ARB were older and more likely to have hypertension, diabetes mellitus, and congestive heart failure. The overall mortality rate was 15.1% (118/781) and increased with age (PTrend<0.0001). The crude odds ratios (ORs) for death for ACEI users and ARB users were 0.98, 95% CI, 0.60-1.60, P=0.9333, and 1.13, 95% CI, 0.67-1.91, P=0.6385, respectively. After adjusting for age, hypertension, diabetes mellitus, and congestive heart failure, antecedent ACEI administration was associated with reduced mortality (OR, 0.55; 95% CI, 0.31-0.98, P=0.0436); a similar, but weaker trend was observed for ARB administration (OR, 0.58; 95% CI, 0.32-1.07, P=0.0796). Conclusions In those aged ≥50 years hospitalized with COVID-19, antecedent use of ACEI was independently associated with reduced risk of inpatient death. Our findings suggest a protective role of renin-angiotensin-aldosterone system inhibition in patients with high cardiovascular risk affected by COVID-19.

Inpatient Mortality According to Level of Respiratory Support Received for Severe Acute Respiratory Syndrome Coronavirus 2 (Coronavirus Disease 2019) Infection: A Prospective Multicenter Study.

OBJECTIVES: To describe patients according to the maximum degree of respiratory support received and report their inpatient mortality due to coronavirus disease 2019. DESIGN: Analysis of patients in the Coracle registry from February 22, 2020, to April 1, 2020. SETTING: Hospitals in the Piedmont, Lombardy, Tuscany, and Lazio regions of Italy. PATIENTS: Nine-hundred forty-eight patients hospitalized for coronavirus disease 2019. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Among 948 patients, 122 (12.87%) received invasive ventilation, 637 (67.19%) received supplemental oxygen only, and 189 (19.94%) received no respiratory support. The median (quartile 1-quartile 3) age was 65 years (54-76.59 yr), and there was evidence of differential respiratory treatment by decade of life (p = 0.0046); patients greater than 80 years old were generally not intubated. There were 606 men (63.9%) in this study, and they were more likely to receive respiratory support than women (p < 0.0001). The rate of in-hospital death for invasive ventilation recipients was 22.95%, 12.87% for supplemental oxygen recipients, and 7.41% for those who received neither (p = 0.0004). A sensitivity analysis of the 770 patients less than 80 years old revealed a lower, but similar mortality trend (18.02%, 8.10%, 5.23%; p = 0.0008) among the 14.42%, 65.71%, and 19.87% of patients treated with mechanical ventilation, supplemental oxygen only, or neither. Overall, invasive ventilation recipients who died were significantly older than those who survived (median age: 68.5 yr [60-81.36 yr] vs 62.5 yr [55.52-71 yr]; p = 0.0145). CONCLUSIONS: Among patients hospitalized for coronavirus disease 2019, 13% received mechanical ventilation, which was associated with a mortality rate of 23%.

Metabolic Alkalosis: A Brief Pathophysiologic Review.

Metabolic alkalosis is a very commonly encountered acid-base disorder that may be generated by a variety of exogenous and/or endogenous, pathophysiologic mechanisms. Multiple mechanisms are also responsible for the persistence, or maintenance, of metabolic alkalosis. Understanding these generation and maintenance mechanisms helps direct appropriate intervention and correction of this disorder. The framework utilized in this review is based on the ECF volume-centered approach popularized by Donald Seldin and Floyd Rector in the 1970s.  Although many subsequent scientific discoveries have advanced our understanding of the pathophysiology of metabolic alkalosis, that framework continues to be a valuable and relatively straightforward diagnostic and therapeutic model.

Evaluation of the safety and efficacy of the central venous administration of potassium chloride including the measurement of intracardiac potassium concentrations.

This study examined the safety and efficacy of the intravenous administration of 20 mEq potassium chloride (KCl) dissolved in a 100 cc 5% dextrose in sterile water bolus over 1 hour through a subclavian central vein catheter in critical care unit patients for the treatment of low and low to normal serum potassium concentrations. We studied seven patients with morning serum potassium between 2.4 and 3.6 mEq/L who had intravenous KCl boluses ordered by their treating physician. Intracardiac and peripheral venous potassium levels were obtained before, during, and after infusion. Holter and electrocardiogram assessment of rhythm, supraventricular and ventricular ectopy, and electrical intervals were recorded before, during, and after the intravenous KCl bolus. The cardiac rhythm, heart rates, and electrocardiographic intervals remained unchanged throughout the infusion and postinfusion phases. In six of the seven patients, there was no new or worsening supraventricular or ventricular ectopy temporally related to the infusion. Postinfusion potassium levels increased in all patients, with an average peripheral vein serum potassium increase of 0.4 mEq/L. In conclusion, within the limitations of our sample size, our study demonstrated the safety and efficacy of the central venous infusion of 20 mEq KCl in 100 cc 5% dextrose in sterile water administered over 1 hour.

Case report: Patiromer-induced hypercalcemia.

Patiromer is a novel potassium-binding compound which has recently received FDA approval. This ion exchange resin releases calcium when it binds potassium. We describe the development of hypercalcemia after initiation of patiromer. The calcium levels fell when the drug was stopped but recurred when it was later resumed. Patiromer was again discontinued, and the serum calcium level fell back into the normal range. We believe this patient manifested patiromer-induced hypercalcemia.

A Model for Glomerular Filtration Rate Assessment in Liver Disease (GRAIL) in the Presence of Renal Dysfunction.

Estimation of glomerular filtration rate (eGFR) in patients with liver disease is suboptimal in the presence of renal dysfunction. We developed a model for GFR assessment in liver disease (GRAIL) before and after liver transplantation (LT). GRAIL was derived using objective variables (creatinine, blood urea nitrogen, age, gender, race, and albumin) to estimate GFR based on timing of measurement relative to LT and degree of renal dysfunction (www.bswh.md/grail). The measured GFR (mGFR) by iothalamate clearance (n = 12,122, 1985-2015) at protocol time points before/after LT was used as reference. GRAIL was compared with the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Modification of Diet in Renal Disease (MDRD-4, MDRD-6) equations for mGFR < 30 mL/min/1.73 m2 . Prediction of development of chronic kidney disease (mGFR < 20 mL/min/1.73 m2 , initiation of chronic dialysis) and listing or receipt of kidney transplantation within 5 years was examined in internal cohort (n = 785) and external validation (n = 68,217, 2001-2015). GRAIL had less bias and was more accurate and precise as compared with CKD-EPI, MDRD-4, and MDRD-6 at time points before/after LT for low GFR. For mGFR < 30 mL/min/1.73 m2 , the median difference (eGFR-mGFR) was GRAIL: 5.24 (9.65) mL/min/1.73 m2 as compared with CKD-EPI: 8.70 (18.24) mL/min/1.73 m2 , MDRD-4: 8.82 (17.38) mL/min/1.73 m2 , and MDRD-6: 6.53 (14.42) mL/min/1.73 m2 . Before LT, GRAIL correctly classified 75% as having mGFR < 30 mL/min/1.73 m2 versus 36.1% (CKD-EPI), 36.1% (MDRD-4), and 52.8% (MDRD-6) (P < 0.01). An eGFR < 30 mL/min/1.73 m2 by GRAIL predicted development of CKD (26.9% versus 4.6% CKD-EPI, 5.9% MDRD-4, and 10.5% MDRD-6) in center data and needing kidney after LT (48.3% versus 22.0% CKD-EPI versus 23.1% MDRD-4 versus 48.3% MDRD-6, P < 0.01) in national data within 5 years after LT. Conclusion: GRAIL may serve as an alternative model to estimate GFR among patients with liver disease before and after LT at low GFR.

Dehydration Polymerization for Poly(hetero)arene Conjugated Polymers.

The lack of scalable and sustainable methods to prepare conjugated polymers belies their importance in many enabling technologies. Accessing high-performance poly(hetero)arene conjugated polymers by dehydration has remained an unsolved problem in synthetic chemistry and has historically required transitional-metal coupling reactions. Herein, we report a dehydration method that allows access to conjugated heterocyclic materials. By using the technique, we have prepared a series of small molecules and polymers. The reaction avoids using transition metals, proceeds at room temperature, the only required reactant is a simple base and water is the sole by-product. The dehydration reaction is technically simple and provides a sustainable and straightforward method to prepare conjugated heteroarene motifs.

Topiramate and metabolic acidosis: an evolving story.

Topiramate is an anticonvulsant that is being increasingly used for a number of different off-label indications. Its inhibition of carbonic anhydrase isoenzymes can lead to metabolic acidosis, elevated urine pH, reduced urine citrate, and hypercalciuria, thereby creating a milieu that is ripe for calcium phosphate stone formation. In this review, we describe a case of topiramate-induced metabolic acidosis. We review the frequency of metabolic acidosis among children and adults, as well as the mechanism of hyperchloremic metabolic acidosis and renal tubular acidosis in topiramate users. Finally, we describe the long-term effects of topiramate-induced metabolic acidosis, including nephrolithiasis, nephrocalcinosis, and bone degradation. Patients who are prescribed topiramate should be carefully monitored for metabolic derangements, and they may benefit from alkali supplementation, or in extreme cases, discontinuation of the drug altogether.

Emergency management of severe hyperkalemia: Guideline for best practice and opportunities for the future.

Hyperkalemia is a common electrolyte disorder, especially in chronic kidney disease, diabetes mellitus, or heart failure. Hyperkalemia can lead to potentially fatal cardiac dysrhythmias, and it is associated with increased mortality. Determining whether emergency therapy is warranted is largely based on subjective clinical judgment. The Investigator Network Initiative Cardiovascular and Renal Clinical Trialists (INI-CRCT) aimed to evaluate the current knowledge pertaining to the emergency treatment of hyperkalemia. The INI-CRCT developed a treatment algorithm reflecting expert opinion of best practices in the context of current evidence, identified gaps in knowledge, and set priorities for future research. We searched PubMed (to August 4, 2015) for consensus guidelines, reviews, randomized clinical trials, and observational studies, limited to English language but not by publication date. Treatment approaches are based on small studies, anecdotal experience, and traditional practice patterns. The safety and real-world effectiveness of standard therapies remain unproven. Prospective research is needed and should include studies to better characterize the population, define the serum potassium thresholds where life-threatening arrhythmias are imminent, assess the potassium and electrocardiogram response to standard interventions. Randomized, controlled trials are needed to test the safety and efficacy of new potassium binders for the emergency treatment of severe hyperkalemia in hemodynamically stable patients. Existing emergency treatments for severe hyperkalemia are not supported by a compelling body of evidence, and they are used inconsistently across institutions, with potentially significant associated side effects. Further research is needed to fill knowledge gaps, and definitive clinical trials are needed to better define optimal management strategies, and ultimately to improve outcomes in these patients.